CHARLESTON, W.Va. -- Workers at NiSource Gas Transmission and Storage had to manually shut off the flow of gas to the pipeline that ruptured, exploded and launched a wall of fire Tuesday over the Sissonville area, investigators from the National Transportation Board have found.

Safety advocates have long argued for mandated installation of automatic or remote shutoff valves on such pipelines, but that requirement is still not on the books - and remains years away under a much-touted new law signed by President Obama in January.

During a U.S. Senate committee hearing in October 2011, former congressional staffer Rick Kessler, testifying on behalf of the Pipeline Safety Trust, recalled lawmakers debating - and then not acting on -- an automatic shutoff device requirement nearly two decades earlier.

"How is it that we shut off our televisions, close our garage doors, and lock our cars by remote control, but somehow we still find it acceptable to shut off a large pipeline spewing fire into a populated neighborhood by finding someone with a key to a locked valve and have that person drive to the valve to shut it off manually?" Kessler told a subcommittee of the Senate Commerce, Science and Transportation Committee, chaired by Sen. Jay Rockefeller, D-W.Va.

So far this week, NiSource officials have refused to answer questions about the shutoff equipment on the pipeline, or about their response to the explosion.

In a website update posted Wednesday, the company said that "working in close coordination with local emergency responders," company teams "had isolated the damaged portion of the line, secured the site and began assessing damages."

Several hours after Tuesday's explosion, Gov. Earl Ray Tomblin praised NiSource's safety systems and the company's quick response in shutting down the gas-flow to the fire.

"The safety measures that are in place, the cutoffs, they worked fine, so immediately after, the pipes, the shutoffs, went into closed mode and the gas shut off," Tomblin told reporters early Tuesday evening.

But later Tuesday night, NTSB investigators said that it took company officials more than an hour to isolate the section of transmission pipeline where the blast occurred, and begin to stem the flow of fuel to the huge fire that erupted over I-77 and nearby homes.

The flow was manually shut off on the west at the Lanham compressor station and at another location east of the explosion site, said C.W. Sigman, Kanawha County's deputy emergency manager and fire coordinator.

"There were no remote-controlled valves or automatic shutoff valves for this line," Peter Knudson, an NTSB spokesman, said Thursday.

NTSB board member Robert Sumwalt said the explosion occurred at 12:41 p.m., and that isolation valves upstream and downstream from the ruptured section of pipeline were activated manually at about 1:45 p.m.

"Part of our investigation will be looking to see if this pipeline was shut down in a reasonable and prudent fashion," Sumwalt said.

Following a September 2010 natural gas transmission pipeline explosion that killed eight people in San Bruno, Calif., the NTSB harshly criticized the emergency response efforts of the pipeline operator, Pacific Gas and Electric Co.

NTSB investigators said in that case, the 95 minutes PG&E took to stop the flow of gas and isolate the ruptured line "was excessively long and contributed to the extent and severity of property damage and [increased] the life-threatening risks to the residents and emergency responders."

In a media briefing Wednesday night, Sumwalt declined to say if NiSource had taken too long to shut down the gas feeding the fire that erupted over Sissonville.

"We have seen cases where there are automatic shutoff valves and remote control valves where the pipeline can be shut off instantaneously if not very, very quickly after that," Sumwalt said. "Recently, we had an oil pipeline spill where it continued to flow for over 17 hours. There is a gamut. It can range from very quickly to a long time."

In its report on the San Bruno disaster, the NTSB urged the federal Department of Transportation to begin requiring automatic shutoff valves on pipeline located in "high consequence areas" where people, property or the environment could be seriously damaged by accidents.

"The use of either automatic shutoff valves or remote control valves would have reduced the amount of time taken to stop the flow of gas," the NTSB said in a report issued in September 2011.

Current rules from the U.S. Department of Transportation require automatic or remote shutoff valves only if pipeline companies themselves determine that installing such devices "would be an efficient means of adding protection" to the public, property and environment in the event of a release.

NTSB investigators noted that PG&E had dismissed the use of automatic or remote shutoff devices, saying that most of the damage from pipeline ruptures occur within the first 30 seconds and that the duration of the resulting fire "has (little) or nothing to do with human safety and property damage." Later, during an NTSB hearing, PG&E's senior engineer testified that conclusion was based on a review on only industry-generated reports, not government or safety group studies that reached different conclusions.

Also, NTSB investigators noted, PG&E had stated years before, during a 1997 public meeting, that safety would be enhanced by reducing the volume of flammable gas released, that a "major technological advantage is the ability to isolate the pipeline break quickly without personnel being required to be sent to operate any mainline valves."

PG&E also later said that using remote control shutoffs could have reduced the time it took to cut the flow of gas to the San Bruno fire from more than 90 minutes to about 30 minutes, the NTSB noted.

In its report, the NTSB said that studies have indicated that prolonged gas-fed fires lead to increased property damage. A congressionally mandated study, published in 1999, found that remote shut-off devices reduced property damage and public disruption, lessened damage to other utilities, and allowed emergency responders faster access to accident sites.

On its website, the transportation department's Pipeline and Hazardous Materials Safety Administration, or PHMSA, lists its response to the NTSB recommendation on shutoff valves as "under development." Agency officials did not return a phone call Thursday.

In August 2011, automatic or remote shutoff valves were among a long list of potential safety reforms that the agency sought public comments on as part of a broader initiative. No proposed rule on shutoff valves has yet emerged from the agency.

Last year, legislation introduced by House and Senate Democrats - including Rockefeller - would have mandated the PHMSA within two years issue a rule to mandate automatic or remote shutoff devices. But the final bill, approved and signed into law, includes language from a competing Republican measure that requires such a rule only if the agency determines it is "appropriate," and applies it only to new or rebuilt pipelines.